# 让用户输入1-100的分数，同时处理非法输入
try:
    score = int(input("请输入学生分数（1-100）："))
    
    # 判定等级
    if 90 <= score <= 100:
        grade = "A（优秀）"
    elif 80 <= score < 90:
        grade = "B（良好）"
    elif 70 <= score < 80:
        grade = "C（中等）"
    elif 60 <= score < 70:
        grade = "D（及格）"
    elif 1 <= score < 60:
        grade = "E（不及格）"
    else:
        grade = "无效分数！请输入1-100之间的数值"
    
    print(f"学生分数：{score} → 等级：{grade}")
except ValueError:
    print("输入错误！请输入整数类型的分数（1-100）")